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.Dd October 31, 2024
.Dt GROUPMEMBER 9
.Os
.Sh NAME
.Nm groupmember
.Nd checks if credentials mandate some group membership
.Sh SYNOPSIS
.In sys/param.h
.In sys/ucred.h
.Ft bool
.Fn groupmember "gid_t gid" "const struct ucred *cred"
.Ft bool
.Fn realgroupmember "gid_t gid" "const struct ucred *cred"
.Sh DESCRIPTION
The
.Fn groupmember
function checks if credentials
.Fa cred
indicate that the associated subject or object is a member of the group
designated by the group ID
.Fa gid .
.Pp
Considered groups in
.Fa cred
are the effective and supplementary groups.
The real group is not taken into account.
.Pp
Function
.Fn realgroupmember
works the same except that it considers instead the real and supplementary
groups, and not the effective one.
.Sh RETURN VALUES
The
.Fn groupmember
and
.Fn realgroupmember
functions return
.Dv true
if the given credentials indicate membership of the group
.Fa gid ,
or
.Dv false
otherwise.
.Sh SEE ALSO
.Xr getgroups 2 ,
.Xr setgroups 2
.Sh AUTHORS
This manual page was initially written by
.An -nosplit
.An Chad David Aq Mt davidc@acns.ab.ca
and was revised by
.An Olivier Certner Aq Mt olce.freebsd@certner.fr .
